1. Field of the Invention
The present invention relates to an ink jet print head that uses heat of an electrothermal conversion element for ejecting ink accommodated in a heat application portion (or pressure chamber) from an ejection opening.
2. Description of the Related Art
EP 1 078 754 discloses an ink jet print head that has two ink supply ports for one ejection opening and in which the ink supplied into a heat application portion through these ink supply ports is ejected from the ejection opening by using heat generated by an electrothermal conversion element. The ink supply ports are formed to be smaller than the ejection opening to prevent foreign matter from entering the heat application portion.
An ink supply port that is smaller than an ejection opening, can prevent foreign substances from getting into the heat application portion, but increases the flow resistance of ink when the ink is supplied again through the ink supply port into the heat application portion after ink ejection (also referred to as a “refill”). So, the ink ejection frequency cannot be increased, making it impossible to enhance the throughput.